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National Energy Efficiency Data Framework (NEED)

What is NEED?

The National Energy Efficiency Data Framework (NEED) combines yearly energy usage data with data about energy efficiency measure installations for homes and non-domestic properties across the UK. NEED was set up by the Department of Energy and Climate Change (DECC), which is now Department for Business, Energy and Industrial Strategy (BEIS), in order to get a better understanding of energy use and energy efficiency in Great Britain’s buildings.

What does NEED tell us?

As NEED contains data about actual energy use in buildings before and after energy efficiency measures are installed, it can be used to understand how energy use changes.

DECC has produced analysis of NEED to see what changes in energy use are observed in homes that install cavity wall insulation, loft insulation, condensing boilers, solid wall insulation and solar PV (electric) panels. According to analysis published in 2015, the median reduction in gas and electricity usage for measures installed in 2013 was:

Energy efficiency measure

Saving (kWh)

£ saving

Sample size

Cavity wall insulation

1,200 (Gas)



Loft insulation

300 (Gas)



Condensing boiler

1,200 (Gas)



Solid wall insulation

2,000 (Gas)



Solar PV

500 (Electricity)



Pound savings calculated by EST using a gas price of 3.63p / kWh for all measures other than Solar PV which uses an average electricity price of 14.33 p/kWh.

Why do the NEED and Energy Saving Trust figures differ?

You will notice that compared to our savings calculations, the savings figures estimated from DECC’s analysis of NEED are considerably smaller. Energy Saving Trust has modelled savings for a range of typical UK dwellings using SAP 2012 (the recognised assessment procedure for estimating the energy consumed by a dwelling), whereas NEED looks at energy usage data provided by energy companies to estimate in-situ changes in usage.

Our estimated savings for householders consider the following:

  • Only one measure is installed in a typical home.
  • The measure is installed fully and to a professional standard (ie no gaps in the insulation).
  • The household continues to heat their home in the same way  (ie at the same temperature and for the same duration) before and after measures installed.

NEED figures differ because their dataset contains:

  • Baseline readings where energy efficiency measures have been installed but not recorded
  • Imperfect and partial installations
  • Records where households “take comfort” following energy efficiency improvements. This means that they heat their home to a warmer temperature or for longer after installing energy efficiency measures, reducing the amount of energy saved.

Each of these factors lead to NEED estimates of savings being smaller than EST’s modelled savings.

What limitations are there to the NEED dataset?

DECC estimate savings by comparing the change in energy use of households who have installed measures with the change in energy use for households who have not installed measures (ie homes where NEED has no record of a measure being installed). However, the NEED dataset does not include records of measures that may have been installed such as:

  • DIY energy efficiency improvements not recorded under a scheme (eg loft insulation)
  • Condensing boilers; other than the small percentage installed under CERT and other government schemes
  • Double glazing
  • Installations occurring under Warm Front after 2008
  • Social housing improvements undertaken independently of government schemes

Whilst the NEED figures rely on observed savings from energy bills, many energy bills are estimated rather than observed. If bills are estimated, then no saving will be observed from the installation of a measure as estimates are based on previous year’s consumption.

How does the Energy Saving Trust calculate savings?

Energy Saving Trust has carried out a number of evidence reviews and field trials to assess the difference between the modelled and in-situ performance of energy saving measures. Results have shown that previous models have overestimated energy saving. For this reason we apply in-situ adjustment factors to all of our modelled savings to account for the difference between actual and modelled use. These reduction factors are based on data gathered from sources including NEED. Details of this can be found on our calculations page.